Environmental Aspects of AD of Sewage Sludge filegasification landfill clay factory ashes landfill...
Transcript of Environmental Aspects of AD of Sewage Sludge filegasification landfill clay factory ashes landfill...
EPROBIO Foggia 8-23 June 2010
BIOSOLIDS
LANDAPPLICATION
ANAEROBICDIGESTION
DEWATERING
COMPOSTING
DEWATERING
THERMALDRYING
CO-DIGESTION
INCINERATION
GASIFICATION
LANDFILL
CLAY FACTORY
Ashes
LANDFILL
BIO-DRYING
OTHERORGANICWASTES
CEMENT FACTORY
ATAD
EPROBIO Foggia 8-23 June 2010
BIOSOLIDS
LANDAPPLICATION
ANAEROBICDIGESTION
DEWATERING
COMPOSTING
DEWATERING
THERMALDRYING
CO-DIGESTION
INCINERATION
GASIFICATION
LANDFILL
CLAY FACTORY
Ashes
LANDFILL
BIO-DRYING
OTHERORGANICWASTES
CEMENT FACTORY
ATAD
ANAEROBIC DIGESTION
• First application of AD
• Advantages
• Possibilities (heat / power)
• Configurations to improve the performance
• Co-digestion
EPROBIO Foggia 8-23 June 2010
Options to improve AD process
1) Hydrolysis: Pretreatments
• Thermal
• Mechanical (ultrasonic)
• Chemical (ozonation, H2O2,etc.)
• Biological (enzymatic)
2) Temperature: TAD
• Increase T of AD to reduce HRT and to incrase
OLR
3) Balance betweenacidogenic and
methanogenic step
• Two-phase digestion
4) Nutrient balance
• Co-digestion with otherwastes
EPROBIO Foggia 8-23 June 2010
Options to improve AD process
1) Hydrolysis: Pretreatments
• Thermal
• Mechanical (ultrasonic)
• Chemical (ozonation, H2O2,etc.)
• Biological (enzymatic)
2) Temperature: TAD
• Increase T of AD to reduce HRT and to incrase
OLR
3) Balance betweenacidogenic and
methanogenic step
• Two-phase digestion
4) Nutrient balance
• Co-digestion with otherwastes
At any option, the improvement will depend on:
- Sludge characteristics (PS/SS)
- HRT used
- Temperature of operation (normally MAD)
EPROBIO Foggia 8-23 June 2010
Mechanical
Biological
Thermal
Chemical
Several effects:
-Solubilization
-Degradation
Improvent ofbiodegradability
Two interest: Increased biogas yield
Less residual sludge
Improvement options: 1) pre-treatments
EPROBIO Foggia 8-23 June 2010
Mètode Cond. de operació Desint. (%) Biogas incr (%) Avantatges Desavantatges
Ultrasònic 10-15 106 J/kg ST 100 30 completa desintegració
intensiva energia
Tèrmic 150-200 ºC/ 30 min. 30-55 15-50 Procés flexible corrosió, olors
Termoquímic 80-150 ºC/30min NaOH (hasta pH12) 5-60 20-55 Relativament
simple
Corrosió, olor, subseguint
neutralització
Biològic* 5-10%; 37-55 ºC & 10-30 hr 5-50 10-20 operació simple,
baixos costs
baixos rendiments,
olors
Oxidatives O3 0.1-0.3g/gSV H2O2 0.5-2g/gSV 90 20-250
Alta eficiència de
desintegració
pH baixo, corrosió, alt cost
* recalcitrància de la part proteica
Improvement options: 1) pre-treatment
EPROBIO Foggia 8-23 June 2010
TREAMENTS ULTRASONIC vs THERMALIncrease (%) on methane production
• More effectiveness:
- Mesofílic conditions - For secondary sludge
• Difference on Investment and operating costs.
Pretreatment US (11.000 kJ/kg)
TT (145ºC/ 30 min)
MAD PS 21.3 11.7 SS 30.0 17.9
TADPS 12.5 16.7SS 21.4 18.3
Improvement options: 1) pre-treatments
EPROBIO Foggia 8-23 June 2010
*
AOX, LAS, PCB’s, PAH, DEHP, NP/NPE
Their removal has been studied underdifferent operating conditions
* Results are complex as depend of the contaminant and
conditions
Removal or transformation (%) of NPE and DEHP with US (■) and TT (■) pretreatments
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DEHP NP NP1EO NP2EO NPE
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DEHP NP NP1EO NP2EO NPE
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DEHP NP NP1EO NP2EO NPE
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DEHP NP NP1EO NP2EO NPE
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PS SS
55-71%53-65%
* In any case there is animprovement
Improvement options: 1) pre-treatments
EPROBIO Foggia 8-23 June 2010
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TT-MAD TT-TAD US-MAD US-TAD
Treatment
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TT-MAD TT-TAD US-MAD US-TAD
Treatment
E (%
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(a) (b)
DEHP NPE
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AOX, LAS, PCB’s, PAH, DEHP, NP/NPE
Their removal has been studied underdifferent operating conditions
* Results are complex as depend of the contaminant and
conditions
* In any case there is animprovement
Improvement options: 1) pre-treatments
EPROBIO Foggia 8-23 June 2010
Thermophilic vs. Mesophilic AD
At low HRT TAD yieldsare much
higher
At high HRT yields are
similar
Values depend on type of sludge
-Pathogen removal higher in TAD (Biosolids Class A)
Better removal of Microcontamiinats% (AOX, LAS, PCB’s, PAH, DEHP,
NP/E)
- More VFA in supernatants
- Worse dewaterability
0102030405060708090
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Mesophilicdigestion
Thermophilicdigestion
Substratesonication
Son+M_dig Son+T_digNap
htha
lene
and
pyr
ene
rem
oval
(%)
EPROBIO Foggia 8-23 June 2010
Temperature range alternance (Tartakovsky et al. 2007)
Incr. 50 % aprox. en CH4 prod.
TAD ranges aresmall to avoidmethanogens
inhibition
Change of temperature
EPROBIO Foggia 8-23 June 2010
BAGRUP DE RECERCA EN
BIOTECNOLOGIA AMBIENTAL
DEPARTAMENT D’ENGINYERIA QUÍMICA
XARXA DE CENTRES
DE SUPORT
A LA INNOVACIÓ
TECNOLÒGICA
Improvement options 3) Two-
phase AD
EPROBIO Foggia 8-23 June 2010
To keep an equilibrium between acidogenic and methanogenic
phases
Can be considered as a biological
pretreatment of AD
Each phase has its own HRT and operting
Temperature
Keith et al., 2006
Acidogènic Methanogenic
Improvement options: 3) two-phase AD
EPROBIO Foggia 8-23 June 2010
M-M does not improve too much VS removal, but firts acidogenic phase reduces significantly the pathogenic
laod
Configuration HRT(d) VSrem (%)
Meso-Meso 3,5+6,5 50-55
Thermo-Meso 2,5+9 61
Thermo-Thermo 2,5 + 5 63
Improvement options: 3) two-phase AD
EPROBIO Foggia 8-23 June 2010
BAGRUP DE RECERCA EN
BIOTECNOLOGIA AMBIENTAL
DEPARTAMENT D’ENGINYERIA QUÍMICA
XARXA DE CENTRES
DE SUPORT
A LA INNOVACIÓ
TECNOLÒGICA
An example with hyperthermophilic conditions
was studied by Wang (1997) and Gavala (2003)
1st phase
70ºC
MAD
TAD
• Improvements: 30-50%
• For PS improvements for TAD
• For SS, improvements for MAD and TAD
HRT and T should be fixed for each
particular mixture
or
Improvement options: 3) two-phase AD
EPROBIO Foggia 8-23 June 2010
Improvement options: 4) Co-digestion
• SS digesters are infra-used
• Biodegr. OM (High VS conc. Offers a good
opportunity) • A single infra-structure is
used
• Eventual nutrient deficit is
compensated
• Eventual inhibitors are diluted
Mata et al., 1989
EPROBIO Foggia 8-23 June 2010
Mata et al., 1989
IC
CAL
DIG
BIOGAS
MEZ
FD
SEL
FORSU
Improvement options: 4) Co-digestion
EPROBIO Foggia 8-23 June 2010
CONCLUSIONS
• DA can improve its yields (biogas productions and VS removal and digestate quality)
•Improvement can be carried out by pretreatments and a significant activity on this
field is underway.
• Improvement options are quite a few and should be carefully studied as many factors are
affecting
EPROBIO Foggia 8-23 June 2010
CONCLUSIONS
• Requirements of land application can favour TAD and possibly pre-treatmnes.
• Directive will have a high influence onthese issues.
Co-digestion is a logical choice, depending on the surroundings, with
important benefits